Process and composition for water-soluble polymers

ABSTRACT

THIS INVENTION COMPRISES WATER-SOLUBLE POLYMERS FROM POLYDIENES HAVING A SUBSTANTIAL AMOUNT OF REPAIRING UNITS WITH PENDENT VINYL GROUPS, SUCH AS HIGH-VINYL POLYBUTADIENE, AND THE PROCESS FOR PREPARING SUCH WATER-SOLUBLE POLYMERS. THE PROCESS INVOLVES THE ANTI-MARKOWNIKOFF ADDITION OF HYDROGEN BROMIDE TO THE PENDENT VINYL GROUPS TO GIVE THE PRIMARY BORMIDE DERIVATIVES GROUPS, WHICH UPON THE ADDITION OF A TERTIARY AMINE, GIVE QUATERNARY AMMONIUM GROUPS WHICH IMPART WATER SOLUBILITY TO THE POLYMERS. THESE PRODUCTS ARE PARTICULARLY USEFUL FOR THE FLOCCULATION OF SOLIDS FROM SUSPENSIONS THEREOF, SUCH AS ELUTRIATED SEWAGE.

United States Patent O 3,647,774 PROCESS AND COMPOSITION FOR WATER-SOLUBLE POLYMERS Frederick J. Webb, Akron, and David P. Tate,Northfield,

Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio NoDrawing. Filed Aug. 29, 1969, Ser. No. 854,321

Int. Cl. C08d 3/06, 5/02, 5/04 US. Cl. 260-942 R 8 Claims ABSTRACT OFTHE DISCLOSURE This invention comprises water-soluble polymers frompolydienes having a substantial amount of repeating units with pendentvinyl groups, such as high-vinyl polybutadiene, and the process forpreparing such water-soluble polymers. The process involves theanti-Markownikoff addition of hydrogen bromide to the pendent vinylgroups to give the primary bormide derivative groups, which upon theaddition of a tertiary amine, give quaternary ammonium groups whichimpart water solubility to the polymers. These products are particularlyuseful for the flocculation of solids from suspensions thereof, such aselutriated sewage.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to water-soluble polymers. More specifically it relates to theprocess of preparing water-soluble polymers from high-vinyl polydienes,such as polybutadiene, by the addition of hydrogen bromide to giveprimary bromide derivatives which are solubilized by reaction withtertiary amines.

Description of related prior art There are a number of references in theprior art to the reaction of halogenated polymers with amines of varioustypes. These are primarily Water-insoluble products which are capable offunctioning as ion-exchange resins. Some of these include halogenatedrubber, such as halogenated natural rubber, halogenated polybutadiene,polychloroprene, polyvinylchloride and the like, reacted with amines.None of the reactions reported have resulted in the formation ofwater-soluble polymers.

G. Salomon and C. Koningsberger, in Rec. Trav. Chim. 69, 711-723 (1950),describe the hydrohalogenation of synthetic and natural rubber toproduce halide derivatives. With a synthetic rubber made from butadieneand styrene, hydrochlorination by these authors produced secondarychloride derivative groups and a small proportion of what is believed tobe a tertiary chloride group. In other attempts by them,hydrobromination of natural rubbber produced the tertiary brominatedproduct, and attempts to prepare the secondary bromination product usingperoxide conditions to effect an anti-Markownikoff reaction wereunsuccessful. Thus, secondary halogenation products and tertiaryhalogenated products have been obtained upon hydrohalogenation ofunsaturated polymers. Moreover, as pointed out above, attempts toreverse the Markownikoff rule to as to produce secondary bromidederivatives instead of the tertiary bromide derivative wereunsuccessful.

In no instance was any reaction reported in which it was possible toprepare by the hydrohalogenation reaction, products in which the halogenwas added to give a primary halide derivative group. Moreover, thereaction of amines with such secondary and tertiary halide derivativesapparently tends to eliminate the halogen without replacement with theamine. Furthermore, in no case has 3,647,774 Patented Mar. 7, 1972 therebeen reported the reaction of an amine with a halogenated polymer inwhich the polymeric reaction product is made water-soluble.

SUMMARY OF THE INVENTION In accordance with the present invention, ithas now been found that water-soluble polymers can be prepared by thehydrobromination of polydiene polymers having a high proportion ofpendent vinyl groups under conditions which effect an anti-Markownikoffaddition, such as in the presence of peroxides, and thereafter reactingthe primary borminated polymer with a tertiary amine. The primarybromine is capable of forming with the amine group a quaternary ammoniumhydrobromide group which imparts water solubility to the polymer. Wheredesired, the bromide form of the quaternary ammonium groups can beconverted to the chloride form by passing a solution of the same throughan an anion exchange resin which has been pretreated to deposit chlorineions in the anion exchange resin.

For the purpose of Water solubility, the polymer should have at least30% of the repeating units therein attached to a quaternary ammoniumgroup, preferably at least 50%. Theoretically, in order for the polymerproduct to have this amount of quaternary ammonium groups in the finalproduct, it is necessary to have at least a corresponding number ofpendent vinyl groups present in the starting polymer. However, since thenumber of pendent vinyl groups may not be completely converted toquaternary ammonium derivative groups, it is generally preferable tostart with at least 30%, preferably at least of the vinyl type butadienerepeating units in the starting polymer.

The molecular weight of the starting polymer is not critical, so long asthe proportion of pendent vinyl groups, and eventually the resultantquaternary ammonium derivative groups, are within the ranges specifiedabove. For use as flocculating agents the quaternary ammonium polymersof this invention advantageously have high molecular weights, that is atleast 25,000, and preferably in the range of 1,000,000-5,000,000 andeven higher.

Although butadiene homopolymers are preferred in the practice of thisinvention, butadiene copolymers can also be used where the comonomersimpart desirable properties and do not detract from the polymerproperties. The comonomers can be other dienes, such as isoprene andchloroprene, but can also be vinyl aryl or isopropenyl aryl compounds orderivatives thereof having alkyl, aralkyl, cycloalkyl or chlorineattached to the aromatic nucleus, and preferably having no more than 20carbon atoms. Typical of these aromatic comonomers are styrene, vinyltoluene, isopropenyl toluene, ethyl styrene, pcyclohexyl styrene, 0-,mand p-Cl-styrene, vinyl napththalene, vinyl methyl naphthalene, vinylbutyl naphthalene, vinyl cyclohexyl naphthalene, isopropenylnaphthalene, isopropenyl isopropyl naphthalene,1-vinyl-4-chloronaphthalene, l-isopropenyl-5-chloronaphthalene, vinyldiphenyl, vinyl diphenylethyl, 4-vinyl-4-methyl-diphenyl,4-vinyl-4-chlorodiphenyl, and the like.

Since the polymer chain may be degraded during the hydrobromination, itis generally desirable to start with butadiene polymers very high inmolecular weight in order to obtain the quaternary ammonium polymers ofdesired molecular weight. Therefore, it is generally desirable to startwith butadiene polymers of at least 100,000 and preferably at least1,000,000.

Preferably such comonomers have no more than 12 carbon atoms. Where suchcomonomers are to be used, generally at least 1%, preferably at least 5%by weight should be used and as much as 50%, preferably no more than 30%may be used.

Preferably the polydiene is a polybutadiene having at least 30%,preferably at least 80% of the Vinyl type of butadiene repeating unitstherein. Moreover, comonomers can be used provided the high proportionof pendent vinyl groups is attained in the copolymer product. Inhomopolymers of butadiene the 30% can refer to either weight percent ornumber of repeating units per 100 repeating units. In copolymers inwhich the comonomer repeating unit has a different weight from thebutadiene repeating unit, the percent is actually given as the weightpercent based on the parts by weight of the total number ofvinylcontaining repeating units contained in 100 parts by weight of thecoploymer.

In the formulas given below, n is an integer representing the number ofpendent vinyl repeating units in the polymer and has a value of at least4 and advantageously represents at least 30% by weight of the repeatingunits in the polymer. Other types of repeating units are present inbutadiene polymers, such as, for example, cis-1,4 and trans-1,4butadiene repeating units, as well as repeating units of any comonomersthat may be present. The other types of repeating units are generallyinterspersed between the pendent vinyl type of repeating unit but canalso be arranged in block formations.

In the hydrobromination step the unsaturation in the cis-l,4 andtrans-1,4 repeating units are also hydrobrominated. However the brominethus added is not displaced to form quaternary groups as is the casewith the primary bromine derivatives resulting from theanti-Markownikoflf hydrobromination of the pendent vinyl groups.Consequently, the greater the proportion of cis and trans repeatingunits, the greater will be the proportion of covalent bonded bromineremaining in the ultimate polymer, and the less water-soluble thepolymer will be. In contrast, the greater the proportion of pendentvinyl repeating units, the greater will be the proportion of brominedisplaced by tertiary amine molecules to give the solubilizingquaternary ammonium radicals having bromine ions associated therewith.

The preparation of the quaternary ammonium polymers of this inventioncan be represented as follows:

n ca- (been, n

Where desired the Bt ion can be replaced by the Clas indicated above, inwhich case both quaternary ammonium repeating units can be representedby the following formula in which X represents Br or Cl":

CHgCH- CH U Oa peroxide, butyl hydroperoxide, t-butylperbenzoate,di-tbutyl diperphthalate, and the like.

Although the number of bromine atoms per polymer molecule in theintermediate polymer and in the quaternized ammonium polymer is the samein view of the fact that the covalently bonded bromine is converted toionic bromine, the interposing of the N(CH or other quaternary ammoniumradical increases the proportion of non-bromine matter in the polymermolecule and thereby reduces the percent by weight of bromine.

The tertiary amines preferred in the practice of this invention aretrimethyl amine and pyridine. Tetramethylethylenediamine anddimethylpiperazine can also be used for quaternization, but since theyare difunctional they cause crosslinking. Therefore these are generallyused in small percentages as chain extenders in conjunction withtrimethylamine or pyridine, particularly when the starting polymers areof low molecular weight or are degraded to low molecular weight duringthe hydrobromination.

The temperatures for the hydrobromination and for the quaternization arenot critical, and merely affect the reaction rate. For practicalreaction rates, temperatures of O-l20 C. can be used, but the range of20-70" C. is found to be most convenient for the hydrobromination andalso for quaternization with the amine.

The hydrobromination is best effected under anhydrous conditions withthe butadiene polymer dissolved in a hydrocarbon solvent, such asbenzene. The hydrogen bromide can be bubbled into the solution until theWeight increase indicates that the desired amount has been added.Reaction is almost instantaneous, but reaction can be continued for atleast 10 minutes. The hydrobrominated polymer can be separated bypouring the solution into methanol.

The tertiary amine is used advantageously in stoichiometric amount or inslight excess of the amount desired to be reacted. The amine isadvantageously used as an aqueous solution, generally l030%, preferably25% by Weight concentration. The hydrobrominated polymer can be added tothis solution as a solid or as a hydrocarbon solution. As thequaternization proceeds, the polymer becomes more soluble and isdissolved in the water. Thus when the solid has all disappeared or whenthe polymer in the hydrocarbon solvent has all been reacted andtransferred to the water solution, quaternization has been completed andthe product is in a water solution convenient for subsequent use.

As previously indicated, these quaternary ammonium polymers areparticularly useful for flocculation of suspensions, such as elutriatedsewage, various other wastes such as mining and ore waste liquids, forhydrodynamic acceleration, lubricant compositions, water solublepackaging compositions, etc., and can be used for making potable waterout of lake and river water. For such purposes the inventor has foundthat flocculation is more efiicient with increased molecular weight ofthe polymer. Advantageously the molecular Weight of the quaternaryammonium polymer is at least 25,000, and preferably at least 1,000,000,and favorably as high as conveniently obtainable.

An elutriated sewage sludge having 6.9% solids and 700% Water with noflocculant requires about '19 minutes filtration to give a filter cakeof 70% water content, which is a product that can be handled and burnedeasily. With the polymers of this invention it is possible to produce aproduct having the water content reduced to 70% within 1.8 minutes; to65% in 3.5 minutes; and to 60% in 8.3 minutes. If these polymers areused on very dilute sewage as it comes into the sewage plant, it ispossible to eliminate settling tanks.

PREFERRED EMBODIMENTS Various methods of practicing the invention areillustrated by the following examples. These examples are intendedmerely to illustrate the invention and not in any sense to limit themanner in which the invention may be practiced. The parts andpercentages recited therein and all through the specification, unlessspecifically provided otherwise, are by weight.

EXAMPLE I A solution of 10 gms. of polybutadiene (100,000 molecularweight and 92% pendent vinyl repeating units) and 3 gms. of benzoylperoxide in 400 ml. of benzene is placed in a 28 oz. bottle and cooledto about C. in an ice bath. Hydrogen bromide is bubbled into thesolution until the weight has increased 10.8 gms. The bottle is sealedwith a cap having a plastic (Teflon) liner and allowed to warm to roomtemperature. Then it is placed in a polymerizer in which the bottle issubmerged in a bath maintained at 50 C. and rotated for a period of 24hours. The bottle is cooled, then opened, and the polymer productcoagulated by pouring the solution into methanol. The recovered polymeris redissolved in benzene, washed twice with water, neutralized withdiluted aqueous potassium hydroxide solution and precipitated inmethanol. Then the polymer is redissolved in benzene, filtered,reprecipitated in methanol air dried and then dried in a vacuum oven at40-50 C. The polymer has a dilute solution viscosity (DSV) of 0.14, 0%gel and 44.57% bromine.

EXAMPLE II A solution of 5 gms. of the hydrobrominated product ofExample I and 200 ml. of benzene is placed in a 12 oz. bottle, cappedand cooled in Dry Ice. Then 10.4 gms. of trimethylamine is distilledinto the bottle through a hollow needle inserted through a rubber capliner in the cap of the bottle. The resulting solution is allowed tostand 68.5 hours at room temperature, during which time a solidseparates. The benzene solution is decanted from the separated solid.(Evaporation of the benzene solution yields a residue of approximately0.1 gm. showing that the polymer product has been substantiallycompletely precipitated from the benzene solution.) The precipitatedreaction product is dissolved in methanol, filtered and the solutionevaporated to dryness. The residue is a transparent, brittle glasslikematerial which is soluble in water. The analysis shows: 4.35% nitrogen,32.45% bromine.

EXAMPLE 11a The procedures of Examples I and II are repeatedsuccessfully using in one case tetrahydrofurane in place of the benzeneas the solvent for the hydrobrornination, and in another case usingbenzene as the solvent, and in both cases adding the trimethylamine as a25% aqueous solution.

EXAMPLE III The polyquaternary ammonium polymer prepared according toExamples LI and Ila is tested as a flocculating agent in an elutriatedsewage sludge having 6.9% solids. A control test is also run using nofiocculant. In each case after the aqueous solution of the fluocculatingagent is added, filtration is effected on an 11 cm. Biichner funnelunder a vacuum of inches of mercury. The time for removal of suflicientwater from the sludge to form a tight cake of 70% moisture isdrastically reduced with the polyquaternary ammonium polymer incomparison with the control.

EXAMPLE 11 1a The procedure of Example III is repeated except that therpolyquaternary ammonium polymer is first converted from the bromide formto the chloride form by passing an aqueous solution of the polymer fromExample II through a column packed with an aminostyrene-divinylbenzenecopolymer anion exchange resin which had previously been treated with anaqueous solution of hydrogen chloride, the amount of resin beingsuflicient to provide at least twice as many amino radicals as thenumber of bromine atoms to be replaced and the amount of hydrogenchloride in solution form passed through the ion exchange bed being atleast twice the stoichiometric amount required to provide enoughchloride for complete reaction with the amino groups. The results of thesewage treatment With the chloride form of the polymer are similar tothose obtained with the bromide form.

EXAMPLE 'IV Similar improvements are noted when the procedures ofExamples IIII are repeated using equivalent amounts of pyridine in placeof the trimethylamine. The polymeric repeating unit structure can berepresented as follows:

1 Br- +l l C H EXAMPLE V Ten parts of the hydrobrominated polymer ofExample I is stirred for 22 hours at room temperature and 10.5 hours at40-50 C. with 1000 ml. of 25 aqueous trimethylamine. The polymer hascompletely dissolved. Evaporation of the resulting light brown solutiongives 11.0 parts of a light brown, transparent, brittle polymer having25.73% bromine and 3.0% nitrogen. Upon testing as a fiocculent as inExample III, excellent results are obtained.

EXAMPLE VI Improved results are also obtained when the procedures ofExamples I, II and III are repeated individually using the followingbutadiene copolymers, in each case the molecular Weight beingapproximately 300,000 and the percent pendent vinyl repeating unitsbeing approximately 70% by weight:

(1) Butadiene-styrene copolymer -20 (2) Butadiene-vinyl toluene 70-30(3) Butadiene-isoprene 80-20 (4) Butadiene-chloroprene 75-25 EXAMPLE VIIThe procedures of Examples I, II and III are repeated a number of timeswith similar results using in place of the benzoyl peroxide in Example Iequivalent amounts respectively of:

(a) Lauroyl peroxide (b) Cumyl peroxide (c) Cumyl hydroperoxide (d)t-Butyl peroxide (e) Di-t-butyl diperphthalate (f) t-Butyl perbenzoateWhile certain features of this invention have been described in detailwith respect to various embodiments thereof, it will, of course, beapparent that other modifications can be made within the spirit andscope of this invention and it is not intended to limit the invention tothe exact details shown above except insofar 'as they are defined in thefollowing claims.

The invention claimed is:

1. A water-soluble quaternary ammonium polymer composition having amolecular weight of 25,000- 5,000,000 and having in the polymer chainthereof a plurality of quaternary ammonium repeating units having aformula selected from the class consisting of:

wherein X- represents Br or Cl and said repeating units comprise atleast 30 percent by weight of the total number of repeating units insaid polymer.

2. The composition of claim 1 in which said repeating units comprise atleast 80 percent by weight of the total number of repeating units insaid polymer.

3. The composition of claim 2 in which X- represents Br.

4. The composition of claim 3 in which the remainder of the repeatingunits in said polymer are essentially butadiene repeating units.

5. The composition of claim 4 in which said polymer has a molecularweight of l,000,000-5,000,000.

6. The process of preparing a quaternary ammonium polymer of claim 1comprising the steps of reacting a butadiene polymer having at least 30percent by weight of pendent vinyl but-adiene repeating units thereinwith hydrogen bromide in an amount at least equivalent to the amount ofsaid vinyl repeating units for which reaction is to be effected and inthe presence of at least a trace amount and up to 30 percent by weightbased on the weight of polymer of a peroxy compound for at least 10minutes, then reacting the hydrobrominated polymer with an amineselected from the class of trimethylamine and pyridine until saidpolymer has become water-soluble.

7. The process of claim 6 in which said polymer is a polybutadienehaving at least 80 percent by weight of pendent-vinyl butadienerepeating units therein and said amine is trimethylamine.

8. The process of claim 7 in which said butadiene polymer has amolecular weight of 1,000,000 to 5,000,000.

References Cited UNITED STATES PATENTS 2,596,878 5/1952 Van Veersen26094.7 X 2,694,702 11/1954 Jones 260-935 JOSEPH L. SCHOFER, PrimaryExaminer W. F. HAMROCK, Primary Examiner US. Cl. X.R.

